Jeff Lawrence on mon 15 nov 99
Hello hummingbirds, bulls and other rodophiliacs,
I had the pleasure of speaking with John Conrad a couple of weeks ago --
bought some equipment from him (very low prices and interesting tools, btw)
and couldn't resist bending his ear a little about copper reds.
This conversation smashed the tablets I've held as gospel.
According to Tichane, the stage is set for reds on a reduction temp climb,
but the atmosphere on the way down doesn't really matter. However, JC told
me about a student of his, Julia Brooks (written up in CM sometime in the
last few years, but I don't have it) who ox-fired crystalline reds in
electric kilns to temp, but reduced all the way down. She rigged a slow oil
drip off a ceramic probe stuck in the kiln. JC: "She got terrific reds."
It's hard to reconcile conflicting expert testimony. Does anyone have
experience with crystalline glazes that shows if they are more open to
later reduction than amorphous glazes? Since most electric-fired
crystalline glazes Ive read contain zinc, might there be a post-Hendley
role for zinc in red formation? Anybody got that CM article handy?
I don't expect a universal red theory, but I'd enjoy hearing about
anybody's duplicable experience or even shoot-from-the-hip theories. Yes, I
know I should be testing, but all I've time for is theorizing.
Jeff
Michael Banks on tue 16 nov 99
Jeff Lawrence wrote: (snip)
> Does anyone have
> experience with crystalline glazes that shows if they are more open to
> later reduction than amorphous glazes? Since most electric-fired
> crystalline glazes Ive read contain zinc, might there be a post-Hendley
> role for zinc in red formation? Anybody got that CM article handy?
Copper-bearing zinc crystalline glazes can be subjected to reduction in the
cooling cycle or in a second reduction firing to ~600-700oC, giving red
crystals on blue, buff, green etc background. The willemite (Zn2SiO4)
crystal rosettes are still open to the glaze surface allowing gas exchange,
while the surrounding gloss glaze is essentially impermeable at low red
heat.
Graeme Anderson included a couple of photographs of post-fire zinc crystal
reduction pots in an article in Ceramics Technical magazine (pp 69-72),
No.1, 1995. If you don't have access to this magazine Jeff, contact me and
I can send you a copy.
Michael Banks,
Nelson,
New Zealand
>
> I don't expect a universal red theory, but I'd enjoy hearing about
> anybody's duplicable experience or even shoot-from-the-hip theories. Yes,
I
> know I should be testing, but all I've time for is theorizing.
>
> Jeff
>
Nils Lou on tue 16 nov 99
Been asked for my new red which has now had several months trial with
students. Seems to be extremely reliable and "easy" to get--hence the name
Nils Lou Easy Red
Cone 9-1/2 (best results)
start reduction at 010 and hold medium to end
soda spar (custer or k-200)--1200
neph sye--440
gerstley borate--320
whiting--320
spodumene--200
silica--500
bentonite--40
tin ox.--30
copper carb--10
red iron ox--5
very stable with little run, little crazing (on pine lake white)
fired routinely in old alpine updraft. Don't fire past 9-1/2
It's very stable.nl
Lana Reeves on wed 17 nov 99
I'd like to try this glaze, but... custer is a potash spar; Kona F-4 is
soda; K-200 is???, and I don't have it anyway. [Have G-200, which is
potash] So, please-- which one to use?
Thanks!
Lana in Somerville, MA
kilnkat@rcn.com =^..^=
-----Original Message-----
From: Nils Lou
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, November 16, 1999 6:28 PM
Subject: Re: Copper reds - brown-potters please ignore
----------------------------Original message----------------------------
Been asked for my new red which has now had several months trial with
students. Seems to be extremely reliable and "easy" to get--hence the name
Nils Lou Easy Red
Cone 9-1/2 (best results)
start reduction at 010 and hold medium to end
soda spar (custer or k-200)--1200
neph sye--440
gerstley borate--320
whiting--320
spodumene--200
silica--500
bentonite--40
tin ox.--30
copper carb--10
red iron ox--5
very stable with little run, little crazing (on pine lake white)
fired routinely in old alpine updraft. Don't fire past 9-1/2
It's very stable.nl
Nils Lou on wed 17 nov 99
It was quickly pointed out by Dannon that neither custer or k-200 are soda
spars. In the tests we used Custer spar. I confess to sloppy copy. nl
On Tue, 16 Nov 1999, Nils Lou wrote:
> ----------------------------Original message----------------------------
> Been asked for my new red which has now had several months trial with
> students. Seems to be extremely reliable and "easy" to get--hence the name
>
> Nils Lou Easy Red
> Cone 9-1/2 (best results)
> start reduction at 010 and hold medium to end
>
> soda spar (custer or k-200)--1200
> neph sye--440
> gerstley borate--320
> whiting--320
> spodumene--200
> silica--500
> bentonite--40
> tin ox.--30
> copper carb--10
> red iron ox--5
>
> very stable with little run, little crazing (on pine lake white)
> fired routinely in old alpine updraft. Don't fire past 9-1/2
> It's very stable.nl
>
Nils Lou on thu 18 nov 99
Sorry for the mix-up. You are perfectly correct. The recipe in the studio
says clearly Custer Spar. In my haste I typed in "soda". It is an age
related defect. Nils
On Wed, 17 Nov 1999, Lana Reeves wrote:
> ----------------------------Original message----------------------------
> I'd like to try this glaze, but... custer is a potash spar; Kona F-4 is
> soda; K-200 is???, and I don't have it anyway. [Have G-200, which is
> potash] So, please-- which one to use?
> Thanks!
> Lana in Somerville, MA
> kilnkat@rcn.com =^..^=
>
> -----Original Message-----
> From: Nils Lou
> To: CLAYART@LSV.UKY.EDU
> Date: Tuesday, November 16, 1999 6:28 PM
> Subject: Re: Copper reds - brown-potters please ignore
>
>
> ----------------------------Original message----------------------------
> Been asked for my new red which has now had several months trial with
> students. Seems to be extremely reliable and "easy" to get--hence the name
>
> Nils Lou Easy Red
> Cone 9-1/2 (best results)
> start reduction at 010 and hold medium to end
>
> soda spar (custer or k-200)--1200
> neph sye--440
> gerstley borate--320
> whiting--320
> spodumene--200
> silica--500
> bentonite--40
> tin ox.--30
> copper carb--10
> red iron ox--5
>
> very stable with little run, little crazing (on pine lake white)
> fired routinely in old alpine updraft. Don't fire past 9-1/2
> It's very stable.nl
>
Debby Grant on thu 18 nov 99
Dear Lana,
You can use your G-200 feldspar as a direct substitute for Custer.
Good Luck, Debby Grant in NH
Veronica Honthaas on fri 19 nov 99
Please clarify what you consider to be cone 9 1/2.
At 06:25 PM 11/16/99 EST, you wrote:
>----------------------------Original message----------------------------
>Been asked for my new red which has now had several months trial with
>students. Seems to be extremely reliable and "easy" to get--hence the name
>
>Nils Lou Easy Red
>Cone 9-1/2 (best results)
>start reduction at 010 and hold medium to end
>
>soda spar (custer or k-200)--1200
>neph sye--440
>gerstley borate--320
>whiting--320
>spodumene--200
>silica--500
>bentonite--40
>tin ox.--30
>copper carb--10
>red iron ox--5
>
>very stable with little run, little crazing (on pine lake white)
>fired routinely in old alpine updraft. Don't fire past 9-1/2
>It's very stable.nl
>
>
Nils Lou on sat 20 nov 99
Half way between cone 9 and cone 10
On Fri, 19 Nov 1999, Veronica Honthaas wrote:
> ----------------------------Original message----------------------------
>
> Please clarify what you consider to be cone 9 1/2.
>
>
>
> At 06:25 PM 11/16/99 EST, you wrote:
> >----------------------------Original message----------------------------
> >Been asked for my new red which has now had several months trial with
> >students. Seems to be extremely reliable and "easy" to get--hence the name
> >
> >Nils Lou Easy Red
> >Cone 9-1/2 (best results)
> >start reduction at 010 and hold medium to end
> >
> >soda spar (custer or k-200)--1200
> >neph sye--440
> >gerstley borate--320
> >whiting--320
> >spodumene--200
> >silica--500
> >bentonite--40
> >tin ox.--30
> >copper carb--10
> >red iron ox--5
> >
> >very stable with little run, little crazing (on pine lake white)
> >fired routinely in old alpine updraft. Don't fire past 9-1/2
> >It's very stable.nl
> >
> >
>
clennell on mon 22 nov 99
The very best red I have found is one I call Mels's grey. Mel will be glad
to send you the formula. It is written up in clay Times - Petes Red.
I ain't sending him the $100 bucks but I am keeping the scotch ready.
cheers,
Tony
Tony and Sheila Clennell
Sour Cherry Pottery
4545 King St.
Beamsville, On. L0R 1B1
http://www.sourcherrypottery.com
e-mail:clennell@bestnet.org
905-563-9382
fax 905-563-9383
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